Adverse childhood experiences (ACEs) such as abuse, bullying or family disruption are increasingly recognised as one of the most potent determinants of later mental health problems. Estimates suggest that mental health problems, including depression and self-harm are at least double among those who have been exposed to ACEs. Despite the recognised importance of ACEs to later mental health outcomes, relatively little is known about the characteristics of ACE’s that have the greatest impact. Firstly, many studies have relied on cumulative scores, whereby ACE’s are simply dichotomised and summed. This approach assumes that each ACE contributes equitably to the outcome of interest and that they operate via the same mechanisms. Other research has focused on the relationship between individual ACEs’ and mental health. Although such studies have provided useful insights, it is known that ACE’s often co-occur and most have failed to take account of this clustering. Person centred approaches such as Latent Class Analysis (LCA) could be used to identify variability in ACE profiles between individuals and investigate potential differential associations with mental health, demographic factors, and mechanisms. Secondly, little attention has been paid to the role of timing, chronicity, or recency of exposure in relation to mental health, and findings from existing studies have been inconclusive. Disentangling these effects is challenging as it may be that those who have been exposed earlier in childhood have also been exposed for longer. This PhD will address these limitations and generate valuable new insights into the relationship between ACEs and two mental health outcomes – depression and self-harm.